If $A$ and $B$ are any two sets,then $(A \cap B)'$ is equal to

Taking the set of natural numbers as the universal set,write down the complement of the following set:
$A = \{ x : x \text{ is a positive multiple of } 3 \}$

The number of subsets of $\{1, 2, 3, \ldots, 9\}$ containing at least one odd number is

If $A$ and $B$ are two given sets,then $A \cap (A \cap B)^c$ is equal to

Taking the set of natural numbers as the universal set,write down the complement of the following set:
$A = \{ x : x \text{ is a prime number} \}$

For each positive real number $\lambda$,let $A_\lambda$ be the set of all natural numbers $n$ such that $|\sin(\sqrt{n+1}) - \sin(\sqrt{n})| < \lambda$. Let $A_\lambda^c$ be the complement of $A_\lambda$ in the set of all natural numbers. Then,